Convertible ladder

ABSTRACT

A convertible ladder including front and rear step sections each including side rails spanned by a plurality of steps, coupling members for selectively connecting the step sections for swinging movement from generally parallel, coextensive positions to relatively inclined positions to configure the step sections as a step ladder or connecting the step sections for generally parallel, sliding movement from coextensive positions to extended positions to configure the step sections as an extension ladder, and a support cradle mounted on the front step section for movement between a removed, inoperative position, which is rearward of the rear step section to permit relative movement of the step sections from the coextensive positions to either the inclined or the extended positions, and a support position underlying a step on the rear step section for supporting the rear step section on the front step section when the front and rear sections are extended.

United States Patent [191 Waldron ,Han. 15, 1974 1 CONVERTIBLE LADDER[76] Inventor: Noel E. Waldron, Rt. No. 1, Elwell,

Mich. 48832 [22] Filed: June 29, 1972 [21] Appl. No.: 267,551

Primary Examiner-Reinaldo P M achado Attorney-John F. Learman et al [57] ABSTRACT A convertible ladder including front and rear step sectionseach including side rails spanned by a plurality of steps, couplingmembers for selectively connecting the step sections for swingingmovement from generally parallel, coextensive positions to relativelyinclined positions to configure the step sections as a step ladder orconnecting the step sections for generally parallel, sliding movementfrom coextensive positions to extended positions to configure the stepsections as an extension ladder, and a support cradle mounted on thefront step section for movement between a removed, inoperative position,which is rearward of the rear step section to permit relative movementof the step sections from the coextensive positions to either theinclined or the extended positions, and a support position underlying astep on the rear step section for supporting the rear step section onthe front step section when the front and rear sections are extended.

2. Qeim Qrex l li sws PATENTED JAN 1 5 i974 SHEET 10F 3 as so 34PATENTEUJAN 1 W V 3.785.455

SHEET 3 BF 3 1 CONVERTIBLE LADDER BACKGROUND OF THE INVENTION Thisinvention relates to a ladder, and more particularly to a convertibleladder which can be configured as either a step ladder or an extensionladder. Accordingly, it is an object of the present invention to providea convertible ladder which can be quickly and easily converted to a stepladder or an extension ladder.

It is another object of the present invention to provide a convertibleladder which includes ladder sections that are swingable betweengenerally parallel coextensive positions and relatively inclinedpositions and apparatus which will automatically move to a lockingposition when the ladder sections are relatively swung betweencoextensive positions and relatively inclined positions to lock the stepsections in the relatively inclined positions.

Yet another object of the present invention is to provide a convertibleladder including a pair of step sections coupled for generally parallelmovement between coextensive and extended positions and swingablesupport apparatus on one of the step sections for supporting the otherstep section when the sections are in the extended positions and beingnormally disposed in the path of a portion of the other step section butwhich is automatically moved to a removed position out of the path ofthe portion on the other section when the sections are being moved toextended positions.

A further object of the present invention is to provide a convertibleladder including a swingable support cradle on a front ladder sectionwhich is movable from a removed, inoperative position rearward of a rearladder section to a support position underlying a portion of the rearladder section to support the rear ladder section on the front laddersection when the sections are relatively longitudinally movedto extendedposition.

A still further object of the present invention is to provide aconvertible step ladder including a cradle of the type mentioned andlocking mechanism for locking the cradle in a position adjacent the rearladder section to prevent the cradle from swinging rearwardly when thestep sections are parallel.

Other objects and advantages of the present invention will becomeapparentas the description thereof proceeds.

SUMMARY OF THE INVENTION A ladder which can be selectively converted toan extension ladder or a step ladder comprising: front and rear stepsections at least one section including a pair of laterally spaced apartrails spanned by a plurality of longitudinally spaced steps; couplingmeans for selectively connecting the sections for either swingingmovement between adjacent, generally parallel, coextensive positions andrelatively inclined positions to configure the ladder as a step ladder,or for generally parallel, longitudinal sliding movement between saidcoextensive positions and extended positions to configure the ladder asan extension ladder; and means for releasably supporting the rearsection on the front section when the sections are in the extendedpositions to releasably preclude movement of the sections from theextended positions to the coextensive positions comprising: rear sectionsupport means mounted on the front section for movement between a remoteinoperative position rearward of the front and rear sections, permittingthe sections to be moved between the coextensive positions and eitherthe extended positions or the relatively inclined positions, to asupport position underlying a portion of the rear section when thesections are in the extended positions.

The present invention may more readily be understood by reference to theaccompanying drawings in which:

FIG. 1 is a side elevational view of a ladder constructed according tothe present invention, part of the side rails being broken away toillustrate more clearly the steps thereon and the position of thelocking member for locking the ladder sections in the positionsillustrated in FIG. 1;

FIG. 2 is a side elevational view of the ladder illustrated in FIG. 1with the ladder sections being illustrated in adjusted, generallyparallel, coextensive positions;

FIG. 3 is a side elevational view similar to FIG. 2, but illustratingthe ladder sections in partially extended positions, part ofa rearladder section side rail being broken away to illustrate more clearlythe support cradle supporting the steps of the rear ladder section;

FIG. 4 is a rear elevational view of the ladder in the partiallyextended configuration illustrated in FIG. 3, the rear ladder sectionbeing illustrated in phantom;

FIG. 5 is a rear elevational view of the rear ladder section only;

FIG. 6 is a sectional plan view of the front ladder section only, takenalong the line 6-6 of FIG. 4;

FIG. 7 is a sectional end view, taken along the line 7-7 of FIG. 4 andillustrating one of the steps on the rear ladder section supported bythe cradle on the front ladder section; and

FIG. 8 is a top plan sectional view of the front ladder section only,taken along the line 88 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT A ladder constructed accordingto the present invention is generally designated 10 and includes a frontstep section, generally designated 12, and a rear step or prop section,generally designated 14. The front step section 12 includes a pair oflaterally spaced, longitudinal side rails 16, spanned by a plurality ofsteps, generally designated 18. The side rails 16 include upper,generally parallel rail portions 16a and lower, downwardly divergingside rail portions 16b for a purpose to be described. Thesteps 18 (FIG. 1) on the front step section 12 each include a generally horizontalfoot supporting section 20 having a rearward, depending terminal lip 20aand an integral, forward, depending reinforcing plate 22 which spans therails 16 and includes a rearwardly bent rib 22a. A trapezoidal cutout 21(FIG. 4) is provided in the lower portion of each of the plates 22interjacent the side rails 16 to provide additional clearance for thefoot of a person climbing the ladder.

The rear ladder section 14 includes a pair of generally parallel siderails 24 spanned by a plurality of steps 26, each exhibiting a generallyinverted U-shaped end cross-section (see FIG. 7) and having a horizontalfoot support portion 26a and a pair of depending leg por tions 26b and26c. With the exception of the uppermost step, the steps are alllongitudinally aligned and the leg portion 26c of each step is flushwith the rear face 24a of the side rails 24. The uppermost step,including the leg portion 266 thereof, is set inwardly of the rear face24a for a purpose to become apparent hereinafter.

The front and rear ladder sections 12 and 14 are coupled together forrelative movement by a pair of coupling members, generally designed 28,which permit the sections 12 and 14 to be swung between the generallycoextensive positions, illustrated in FIG. 2 and the relatively inclinedpositions, illustrated in FIG. 1. The coupling members 28 comprise apair of vertical support plates 30 (see FIGS. 1 and 8), fixed to theupper ends of the front section side rails 16, pivotally mounting a pairof rear ladder section guides 32 by pins 33. The guides 32 includevertical side plates 34 and integral front and rear guide plates 35 and36 which embrace the rear and front surfaces 24a and 24b, respectively,of the rear section side rails 24.

The vertical side plates 34 of the guides 30 are provided with a pair ofupwardly opening notches 38 for receiving a pair of laterally outwardlyextending support pins 40, provided at the upper ends of the side rails24 on the rear ladder section 14, when the ladder sections are in thecoextensive positions, illustrated in FIG. 2, and the relativelyinclined positions illustrated in FIG. 1. The rear ladder section 14,which is supported on the ladder section 12 by the support pins 40,swings about the pivot pins 33 as it is moved from the position shown inFIG. 1 to the position shown in FIG. 2.

Apparatus, generally designated 42, is provided for removably lockingthe ladder sections 12 and 14 in the relatively inclined positionsillustrated in FIG. 1 and comprises a pair of latch arms 44 (FIGS. 1 and4), pivotally mounted on one of the front ladder section steps by pivotpins 48 and spanned by a cross member 50. The latch arms 44 includelaterally inwardly turned latching hooks 52 having terminal ends 53which ride along the rear surfaces 24a of the rear ladder section siderails 24. Recesses 54 are provided in the rear leg 26c of one of thesteps 26 and the rear surfaces 24a of the side rails 24 to receive theterminal ends 53 of the latching hooks 52. The latching hooks 52 areprovided with downwardly opening notches 56 which are received on theedge portions 54a of the rear leg 26c adjacent the cutouts 54.

The ladder section latching arms 44 are mounted internally of thediverging front ladder rail portions 16b and extend externally of therear ladder section rails 24. The latching hooks 52 ride upwardly alongthe rear rail surfaces 24a when the sections 12 and 14 are swung apartuntil the ends 53 are received in the cutouts 54 and the notches 56 arereceived on the upper edge portions 54a of the cutouts 54. With thelatching arms 44 locked in the position illustrated in FIG. 1, theladder sections 12 and 14 cannot be swung toward and away from eachother about the pivot pins 33 and thus a very safe step ladder isprovided.

When the sections 12 and 14 are to be moved from the relatively inclinedpositions illustrated in FIG. 1, to the coextensive positionsillustrated in FIG. 2, the latching arms 44 are moved upwardly from thepositions illustrated in FIG. 1 so that the notches 56 are clear of theupper edge portions 54a of the notches 54 and the ladder sections 14 and12 are swung together about the pivot pins 33. The latching arms 44 fallby gravity and the hook-shaped portions 53 ride along the rear railsurfaces 24a to return to the positions illustrated in FIG. 1.

The rear ladder section guide members 32 slidably receive the rearladder section side rails 24 and permit the side rails 24 to slidevertically, when the sections 12 and 14 are in the parallel relation, tomove between the coextensive positions, illustrated in FIG. 2, and theextended positions, illustrated in FIG. 3. A pair of guide plates 37 arealso provided on the front ladder section side rails 16 below the guides32 to assist in guiding the rear ladder section 14 as it is movedvertically between the position illustrated in FIG. 2 and the positionillustrated in FIG. 3.

For supporting the rear ladder section 14, in the extended positionillustrated in FIG. 3, a cradle, generally designated 60, is providedand includes a pair of support arms 62 pivotally connected to the frontladder section 12 by pivot pins 63 and spanned by an angle member 64having a pair of laterally spaced apart, hook-shaped members 66depending therefrom and defining upwardly opening pockets 68 forreceiving the legs 260 of the steps 26 on the rear ladder section 14.The cradle supported hook members 66 are normally disposed in the pathof the rear ladder section steps 26 and includes a lower camming surface69 engageable by the steps 26 as the rear ladder section 14 is movedupwardly relative to the front ladder section 12 to cam the cradlerearwardly, from the position illustrated in solid lines in FIG. 3, tothe removed position, illustrated in chain lines in FIG. 3, and permitthe ladder sections to be extended. After a step 26 moves past the hookmembers 66, the cradle 60 will fall by gravity into the positionillustrated in FIG. 3 to be disposed in the path of the rear legs 26c ofthe steps 26 when the ladder section 14 is lowered. The lower edge 26d(FIG. 7) of the legs 260 on one of the steps 26 is received in thecradle pockets 68 to preclude movement of the ladder section 14 from theextended position illustrated in FIG. 3 to the coextensive positionsillustrated in FIG. 2. The upper ends 66b (FIG. 7) of the terminalportions 66a of the hook-shaped member 66 terminate below the underside64a (FIGS. 4 and 8) of the angle member 64. A gap g (FIG. 4) is providedbetween the hook members 66 so that an individual can manually grasp therear leg 260 between the hook members 66 and support the lower end 26dthereof above the upper terminal ends 66a of the hooks 66 and lower theleg 260 into the cradle pockets 68 without pinching an individuals handsbetween the steps 26 and the hook members 66.

To reconfigure the ladder as illustrated in FIG. 2, the rear laddersection 14 is moved upwardly so that the lower end 26d of the leg 26csupported on the cradle 60 is above the upper ends 66b of the cradlehooks 66 and the cradle 60 is manually swung outwardly about the pivotpins 63 to the chain line position illustrated in FIG. 3, permitting thedownward movement of the ladder section 14 relative to the laddersection 12.

Apparatus, generally designated 70, is provided for locking the supportcradle 60 in the position illustrated in solid lines in FIG. 3, toabsolutely preclude relative swinging movement of the ladder sections 12and 14 and comprises a pair of independent locking arms 72 pivotallymounted on the front ladder section side rails 16 by pivot pins 74. Thecradle locking arms 72 include downwardly opening notches or recesses 76which are received on the upstanding portion 64b of the angle member 64on the cradle 60, as illustrated in FIG. 7, overlying one of the steps26.

The upper step 26 is positioned so that the rear leg 26c thereof is setinwardly of the rear face 24a of the rear ladder section 14 out of thepath of the cradle hook members 66 to preclude the depending step legportion 260 from being received in the hook-shaped members 66 of thecradle 60 so that the free swinging movement of the cradle 60 will notbe inhibited by the upper step 26. r

A support platform, generally designated 78, is provided for supportingpaint buckets and the like, and includes a generally horizontal supportplate 80 mounted on the flange 640 of the cradle angle member 64 by apair of support members (not shown).

THE OPERATION The ladder will normally be stored in the configurationillustrated in FIG. 2 wherein the front and rear ladder sections 12 and14 are generally coextensive with each other. If the ladder is to beused as a step ladder, the cradle lock members 72 are swung from thesolid line positions, illustrated in FIG. 2, to the solid line positionsillustrated in FIG. 1, to release the cradle 60 for free swingingmovement. The rear ladder sections 14, which is supported on the frontladder section 12 by pins 40, is swung outwardly relative to the section12 about the pivot pin 33 to the position illustrated in FIG. 1. As therear ladder section 14 moves outwardly relative to the ladder section12, the latching hooks 52 of the ladder section latching arms 44 ridealong the rear surface 24a of the rails 24 until the hooks 52 arereceived in the recesses 54 after which time the latching arms 44 maydrop by gravity or be manually forced downwardly so that the notches 56in the latching arms 44 are received on the upper ends 54a of the rearstep portions 260 adjacent the recesses 54.

When it is desired to return the ladder sections to their coextensivepositions, illustrated in FIG. 2, the latching arms 44 are movedupwardly so that the notches 56 therein clear the upper ends 54a of thestep portion 26c and the ladder section 14 is swung about the pivot pins33 until the sections 12 and 14 are generally parallelas viewed in FIG.2. The latching arms 44 will automatically drop under their own weightto th positions illustrated in FIG. 2.

If the ladder is to be configured as an extension ladder, the rearladder section 14 is moved upwardly and the steps 26 engage the camsurface 69 on the underside of the cradle hooks 66 to cam themrearwardly to the removed position illustrated in chain lines in FIG. 3.As soon as the second uppermost step 26 has cleared the upper ends 66aof the cradle hooks 66, the cradle 60 will swing downwardly to the solidline position illustrated in FIG. 3, underlying the leg 26c of thesecond uppermost step 26. The rear ladder section 14 is then slightlylowered so that the rear leg 26c of the second uppermost step 26 isreceived in the recesses or pockets 68 on the hooks 66. The cradlelocking members 72 are then swung from the inoperative positionsillustrated in FIG. 1, to the cradle locking positions illustrated inFIG. 3, so that the notches 76 receive the flange portion 64b of thecradle angle member 64. The ladder then may be positioned against a wallor the like so that the upper ends of the side rails 24 are positionedagainst the wall. The ladder can, of course, be extended to a pluralityof different heights and the cradle used to support any of the steps 26with the exception of the uppermost step.

When the ladder is to be returned to the coextensive configurationillustrated in FIG. 2, the cradle locking hooks 72 are swung to theinoperative position illustrated in FIG. 1, the ladder section 14 ismoved upwardly slightly so that the lower end 26d of the step leg 26creceived in the cradle pockets 68 is positioned above the upper ends6617 of the cradle hooks 66, and the support cradle 60 is swung to thechain line position illustrated in FIG. 3. The rear ladder section 14 islowered to the position illustrated in FIG. 2 so that the rear laddersection 14 is supported by the pins 40 on the front ladder section 12.The cradle locking hooks 72 are then swung from the positionsillustrated in FIG. 1 to the positions illustrated in FIG. 3 and theladder may again be stored.

It is to be understood that the drawings and descriptive matter are inall cases to be interpreted as merely illustrative of the principles ofthe invention, rather than as limiting the same in any way, since it iscontemplated that various changes may be made in various elements toachieve like results without departing from the spirit of the inventionor the scope of the appended claims.

What is claimed is:

l. A ladder which can be selectively converted to either an extensionladder or a step ladder comprising:

front and rear ladder sections each including a pair of laterally spacedapart rails spanned by a plurality of longitudinally spaced steps;

coupling means connecting said ladder sections for either swingingmovement between adjacent, generally parallel, coextensive positions, inwhich said ladder is configured as an extension ladder, and relativelyinclined positions, in which said ladder is configured as a step ladder,or for generally parallel, longitudinal sliding movement between saidcoextensive positions and extended, generally parallel positions;

means for releasably supporting said rear ladder section on the rearface of said front ladder section when said sections are in saidextended, generally parallel positions to releasably preclude movementof said sections from said extended, generally parallel positions tosaid coextensive, generally parallel positions comprising:

rear ladder section support means including a portion mounted on saidfront ladder section for movement between a removed inoperative positionrearward of said front and rear sections, permitting said sections to bemoved from said extended positions to said coextensive positions, and asupport position underlying a portion of said rear ladder section topreclude relative movement of said ladder sections from said extendedpositions to said coextensive positions; and

means for removably locking said sections in said inclined positionsincluding latch means mounted on said front section for swingingmovement between a lowered position and a raised, locking position inresponse to said sections moving toward and away from each other betweensaid coextensive positions and said inclined positions.

2. A ladder which can be selectively converted to either an extensionladder or a step ladder comprising:

front and rear ladder sections each including a pair of laterally spacedapart rails spanned by a plurality of longitudinally spaced steps;

coupling means connecting said ladder sections for either swingingmovement between adjacent, generally parallel, coextensive positions, inwhich said ladder is configured as an extension ladder, and relativelyinclined positions, in which said ladder is configured as a step ladder,or for generally parallel, longitudinal sliding movement between saidcoextensive positions and extended, generally parallel positions; and

means for releasably supporting said rear ladder section on the rearface of said front ladder section when said sections are in saidextended, generally parallel positions to releasably preclude movementof said sections from said extended, generally parallel positions tosaid co-extensive, generally parallel positions comprising:

rear ladder section support means including a portion mounted on saidfront ladder section for movement between a removed inoperative positionrearward of said front and rear sections, permitting said sections to bemoved from said extended positions to said coextensive positions, and asupport position underlying a portion of said rear ladder section topreclude relative movement of said ladder sections from said extendedpositions to said coextensive positions; and

latch means movable to and from a position in which it prevents saidsupport means from moving from said support position and prevents saidladder sections from spreading.

3. The ladder as set forth in claim 2 wherein said latch means isswingably mounted on said front section to and from a position hookedover a portion of said support means when said support means is in saidsupport position.

4. The ladder as set forth in claim 2 wherein said support meansunderlies the steps of said rear ladder section when said support meansis in said support position.

5. The ladder as set forth in claim 2 wherein said support meansincludes a portion, normally in the path of a portion of said rearladder section to prevent movement of said rear ladder section from saidextended position to said coextensive position, swingable to a removedposition out of said path when said rear ladder section is moving tosaid extended position.

6. The ladder as set forth in claim 2 wherein said rear ladder portionsupport means is normally disposed in the path of a portion of said rearladder section when said rear ladder section is moving between saidextended position and said coextensive position to normally precluderelative movement of said sections from said extended positions to saidcoextensive positions, but is movable to said removed position inresponse to relative movement of said sections from said coextensivepositions to said extended positions.

7. The ladder set forth in claim 2 wherein said rear ladder sectionsupport means comprises cradle means swingably mounted on said frontladder section for swinging movement with said rear section when saidsections are relatively moved to said inclined positions.

8. The ladder set forth in claim 2 wherein said support means comprisescradle means, normally disposed in the path of the steps on said rearladder section for interrupting movement of said sections from saidextended positions to said coextensive positions, swingable outwardlyaway from said sections out of the path of the steps on said rear laddersections, to permit relative movement of said sections.

9. The ladder set forth in claim 8 wherein said support means includesclamp means swingably mounted on said front section for swingingmovement to and from a locking position for selectively preventing saidcradle means from swinging rearwardly away from said sections.

10. The ladder set forth in claim 9 wherein said cradle means supportsthe underside of one step of said rear ladder section and said clampmeans overlies said one step in said locking position.

11. The ladder set forth in claim 8 wherein said support means includesmeans on said cradle means movable outwardly away from said sections inresponse to said sections being relatively moved to said extendedpositions.

12. The ladder set forth in claim 11 wherein said cradle means includesupwardly opening hook means for supporting the steps of said rearsection on said front section, said hook means including means reactingwith the steps of said rear section when said sections are relativelymoved to said extended positions to move said cradle means out of saidpath.

13. The ladder set forth in claim 11 wherein the steps on said rearsection each comprise at least one generally horizontal foot supportportion and a generally vertical flange portion receivable in saidcradle means.

14. The ladder set forth in claim 13 wherein the lower end of the flangeportion of the uppermost step of said rear section is positionedforwardly, out of the path, of the cradle means so as not to be receivedby said cradle means when said sections are relatively moved.

15. The ladder set forth in claim 14 wherein said cradle means includesa pair of laterally spaced apart hook-shaped portions spanned by a crossmember, the terminal ends of said hook-shaped portions terminating belowthe underside of said cross member when said cradle means is in the pathof the steps on the rear ladder section to permit the vertical flange ona step of said rear section to be moved to a position above saidhook-shaped members.

16. The ladder set forth in claim 2 including means for removablylocking said sections in said inclined positions including latch meansmounted on said from section for swinging movement between a loweredposition and a raised locking position in response to movement of saidsections toward and away from each other between said coextensive andinclined positions, and means on said rear section for receiving aportion of said latching means to removably lock said latching means insaid locking position and preclude swinging movement of said sectionstoward and away from each other.

17. The ladder set forth in claim 16 wherein said latching meansincludes follower means riding on said rear ladder section for upwardmovement to a locking position as said sections are relatively spread tosaid inclined positions; said receiving means comprising recess meansfor receiving a portion of said latching means in said locking position.

18. A ladder comprising:

a step section including a pair of laterally spaced apart side railsspanned by a plurality of longitudinally spaced steps;

a prop section including a pair of laterally spaced apart side railsspanned by bracing members;

coupling means connecting said sections for relative swinging movementbetween adjacent, generally parallel positions and relatively inclined,spread positions in which said prop section will steady said stepsection; and

means for removably locking said sections in said spread positionsincluding:

locking means pivotally mounted on one of said sections swingableupwardly from an inoperative position to a locking position in responseto spreading of said sections; and

means on said other of said sections for releasably preventing movementof said locking means from said locking positions.

19. The ladder set forth in claim 14 wherein said pivotally mountedmeans includes follower means riding on the rails of said other sectionto and from said locking position.

20. The ladder set forth in claim 19 wherein the side rails of said stepsection include downwardly diverging portions, said locking meansincluding a pair of support arms pivotally mounted on the insideportions of the side rails of said step section and extending laterallyoutwardly of the side rails of said prop section.

21. The ladder set forth in claim 20 wherein said portion of saidlocking means is disposed at the terminal end of said support meanslaterally inwardly of said support arms.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pate 3, 785,455 7Dated January 15, 1974 Inventor-( N081 E. Waldron It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

In Column 7, line 48, delete. "portion"; same line, after "means" insertportion Signed and "sealed this 17th day of September 1974.

(SEAL) Attest: v

McCOY M. GIBSON JR. c. MARSHALL DANN Commissioner of Patents AttestingOfficer OP P040250 (10-69) uscoMM-oc 60376-P69 U,S, GOVERNMENT PRINTINGOFFICE 1 I969 0-366-334,

1. A ladder which can be selectively converted to either an extensionladder or a step ladder comprising: front and rear ladder sections eachincluding a pair of laterally spaced apart rails spanned by a pluralityof longitudinally spaced steps; coupling means connecting said laddersections for either swinging movement between adjacent, generallyparallel, coextensive positions, in which said ladder is configured asan extension ladder, and relatively inclined positions, in which saidladder is configured as a step ladder, or for generally parallel,longitudinal sliding movement between said coextensive positions andextended, generally parallel positions; means for releasably supportingsaid rear ladder section on the rear face of said front ladder sectionwhen said sections are in said extended, generally parallel positions toreleasably preclude movement of said sections from said extended,generally parallel positions to said coextensive, generally parallelpositions comprising: rear ladder section support means including aportion mounted on said front ladder section for movement between aremoved inoperative position rearward of said front and rear sections,permitting said sections to be moved from said extended positions tosaid coextensive positions, and a support position underlying a portionof said rear ladder section to preclude relative movement of said laddersections from said extended positions to said coextensive positions; andmeans for removably locking said sections in said inclined positionsincluding latch means mounted on said front section for swingingmovement between a lowered position and a raised, locking position inresponse to said sections moving toward and away from each other betweensaid coextensive positions and said inclined positions.
 2. A ladderwhich can be selectively converted to either an extension ladder or astep ladder comprising: front and rear ladder sections each including apair of laterally spaced apart rails spanned by a plurality oflongitudinally spaced steps; coupling means connecting said laddersections for either swinging movement between adjacent, generallyparallel, coextensive positions, in which said ladder is configured asan extension ladder, and relatively inclined positions, in which saidladder is configured as a step ladder, or for generally parallel,longitudinal sliding movement between said coextensive positions andextended, generally parallel positions; and means for releasablysupporting said rear ladder section on the rear face of said frontladder section when said sections are in said extended, generallyparallel positions to releasably preclude movement of said sections fromsaid extended, generally parallel positions to said co-extensive,generally parallel positions comprising: rear ladder section supportmeans including a portion mounted on said front ladder section formovement between a removed inoperative position rearward of said frontand rear sections, permitting said sections to be moved from saidextended positions to said coextensive positions, and a support positionunderlying a portion of said rear ladder section to preclude relativemovement of said ladder sections from said extended positions to saidcoextensive positions; and latch means movable to and from a position inwhich it prevents said support means from moving from said supportposition and prevents said ladder sections from spreading.
 3. The ladderas set forth in claim 2 wherein said latch means is swingably mounted onsaid front section to and from a position hooked over a portion of saidsupport means when said support means is in said support position. 4.The ladder as set forth in claim 2 wherein said support means underliesthe steps of said rear ladder section when said support means is in saidsupport positioN.
 5. The ladder as set forth in claim 2 wherein saidsupport means includes a portion, normally in the path of a portion ofsaid rear ladder section to prevent movement of said rear ladder sectionfrom said extended position to said coextensive position, swingable to aremoved position out of said path when said rear ladder section ismoving to said extended position.
 6. The ladder as set forth in claim 2wherein said rear ladder portion support means is normally disposed inthe path of a portion of said rear ladder section when said rear laddersection is moving between said extended position and said coextensiveposition to normally preclude relative movement of said sections fromsaid extended positions to said coextensive positions, but is movable tosaid removed position in response to relative movement of said sectionsfrom said coextensive positions to said extended positions.
 7. Theladder set forth in claim 2 wherein said rear ladder section supportmeans comprises cradle means swingably mounted on said front laddersection for swinging movement with said rear section when said sectionsare relatively moved to said inclined positions.
 8. The ladder set forthin claim 2 wherein said support means comprises cradle means, normallydisposed in the path of the steps on said rear ladder section forinterrupting movement of said sections from said extended positions tosaid coextensive positions, swingable outwardly away from said sectionsout of the path of the steps on said rear ladder sections, to permitrelative movement of said sections.
 9. The ladder set forth in claim 8wherein said support means includes clamp means swingably mounted onsaid front section for swinging movement to and from a locking positionfor selectively preventing said cradle means from swinging rearwardlyaway from said sections.
 10. The ladder set forth in claim 9 whereinsaid cradle means supports the underside of one step of said rear laddersection and said clamp means overlies said one step in said lockingposition.
 11. The ladder set forth in claim 8 wherein said support meansincludes means on said cradle means movable outwardly away from saidsections in response to said sections being relatively moved to saidextended positions.
 12. The ladder set forth in claim 11 wherein saidcradle means includes upwardly opening hook means for supporting thesteps of said rear section on said front section, said hook meansincluding means reacting with the steps of said rear section when saidsections are relatively moved to said extended positions to move saidcradle means out of said path.
 13. The ladder set forth in claim 11wherein the steps on said rear section each comprise at least onegenerally horizontal foot support portion and a generally verticalflange portion receivable in said cradle means.
 14. The ladder set forthin claim 13 wherein the lower end of the flange portion of the uppermoststep of said rear section is positioned forwardly, out of the path, ofthe cradle means so as not to be received by said cradle means when saidsections are relatively moved.
 15. The ladder set forth in claim 14wherein said cradle means includes a pair of laterally spaced aparthook-shaped portions spanned by a cross member, the terminal ends ofsaid hook-shaped portions terminating below the underside of said crossmember when said cradle means is in the path of the steps on the rearladder section to permit the vertical flange on a step of said rearsection to be moved to a position above said hook-shaped members. 16.The ladder set forth in claim 2 including means for removably lockingsaid sections in said inclined positions including latch means mountedon said front section for swinging movement between a lowered positionand a raised locking position in response to movement of said sectionstoward and away from each other between said coextensive and inclinedpositions, and means on said rear section for receiving a portion ofsaid latching means to Removably lock said latching means in saidlocking position and preclude swinging movement of said sections towardand away from each other.
 17. The ladder set forth in claim 16 whereinsaid latching means includes follower means riding on said rear laddersection for upward movement to a locking position as said sections arerelatively spread to said inclined positions; said receiving meanscomprising recess means for receiving a portion of said latching meansin said locking position.
 18. A ladder comprising: a step sectionincluding a pair of laterally spaced apart side rails spanned by aplurality of longitudinally spaced steps; a prop section including apair of laterally spaced apart side rails spanned by bracing members;coupling means connecting said sections for relative swinging movementbetween adjacent, generally parallel positions and relatively inclined,spread positions in which said prop section will steady said stepsection; and means for removably locking said sections in said spreadpositions including: locking means pivotally mounted on one of saidsections swingable upwardly from an inoperative position to a lockingposition in response to spreading of said sections; and means on saidother of said sections for releasably preventing movement of saidlocking means from said locking positions.
 19. The ladder set forth inclaim 14 wherein said pivotally mounted means includes follower meansriding on the rails of said other section to and from said lockingposition.
 20. The ladder set forth in claim 19 wherein the side rails ofsaid step section include downwardly diverging portions, said lockingmeans including a pair of support arms pivotally mounted on the insideportions of the side rails of said step section and extending laterallyoutwardly of the side rails of said prop section.
 21. The ladder setforth in claim 20 wherein said portion of said locking means is disposedat the terminal end of said support means laterally inwardly of saidsupport arms.